Laundry treating apparatus with heat pump and control method thereof

ABSTRACT

A laundry treating apparatus having a heat pump may include a drum, and a heat pump that cools air received from the drum and then heats the cooled air. A heater may heat air transmitted from the heat pump to the drum. A sensing device may sense a state of a heating medium, such as temperature or pressure, and a controller may control the heater based on the sensed state of the heating medium. Speed drying may be performed, energy efficiency may be increased, and durability of the heat pump may be enhanced.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority under 35 U.S.C. §119 to Korean Application No. 10-2012-0117474 filed on Oct. 22, 2012, whose entire disclosure is hereby incorporated by reference.

BACKGROUND

1. Field

This relates to a laundry treating apparatus having a heat pump and an operation method thereof, and more particularly, to a laundry treating apparatus having a heat pump and a control method thereof.

2. Background

A laundry treating apparatus may apply hot air to laundry which has been completely washed and spin-dried to evaporate moisture from the laundry to dry it. In the case of a dryer, a drum may be rotatably installed within a body, and may include a driving motor for driving the drum, a blower blowing air into the drum, and a heater for heating air introduced into the interior of the drum. The heater may use high temperature electrical resistance heat or combustion generated by burning gas. Air released from the drum contains moisture absorbed from the laundry within the drum, thus having high temperature and humidity.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein:

FIG. 1 is a perspective view of an internal structure of a laundry treating apparatus according to an embodiment as broadly described herein;

FIG. 2 is a schematic view of a heat pump and a sensing device of the laundry treating apparatus illustrated in FIG. 1;

FIG. 3 is a block diagram of a system for controlling a heating device of the laundry treating apparatus illustrated in FIGS. 1 and 2;

FIG. 4 is a flow chart of a process of controlling the heating device according to temperature using the control system illustrated in FIG. 3.

FIG. 5 is a flow chart of a process of controlling the heating temperature using the control system illustrated in FIG. 3, according to another embodiment as broadly described herein;

FIG. 6 is a schematic view of a heat pump and a sensing device according to another embodiment as broadly described herein;

FIG. 7 illustrate a temperature sensing device installed in a condenser shown in FIG. 6;

FIG. 8 is a flow chart of a process of controlling the heating device according to temperature using a control system illustrated in FIG. 6;

FIG. 9 is a schematic view of a heat pump and a sensing device according to another embodiment as broadly described herein;

FIG. 10 is a schematic view of a heat pump and a sensing device according to another embodiment;

FIG. 11 is a schematic view of a heat pump and a sensing device according to another embodiment of the present invention;

FIG. 12 is a block diagram of a system for controlling a heating device of the embodiment illustrated in FIGS. 9 to 11;

FIG. 13 is a flow chart of a process for controlling a heating device according to pressure by the control system illustrated in FIG. 12.

FIG. 14 is a flow chart of a method for controlling a laundry treating apparatus according to an embodiment as broadly described herein; and

FIG. 15 is a flow chart of a method for controlling a laundry treating apparatus according to another embodiment as broadly described herein.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings such that they can be easily practiced by those skilled in the art. If a detailed explanation for a related known function or construction is considered unnecessary, such explanation will be omitted as it would be understood by those skilled in the art.

Dryers may be classified into a condensing type dryer (or circulating dryer) and an exhaust-type dryer according to the way in which high temperature and humidity air is treated. In the case of the condensing type dryer, high temperature and humidity air is circulated, rather than being discharged to the outside, so as to be cooled to have a temperature lower than a dew-point temperature, thus condensing moisture included in the high temperature and humidity air. In the case of the exhaust-type dryer, high temperature and humidity air which has passed through the drum is directly discharged to the outside.

In a condensing type dryer, in order to condense air discharged from the drum, air may be cooled to below a dew point, and before it is supplied again to the drum, may be heated by a heater. In this case, as air is cooled during the condensing process, thermal energy of the air is lost, and an extra heater is employed to heat air to a temperature sufficient for drying.

In an exhaust-type dryer, high temperature and humidity air is discharged to the outside, and room temperature ambient air is heated to a required temperature by a heater. In particular, high temperature air discharged to the outside contains thermal energy, but since it is discharged to the outside, efficiency is somewhat degraded.

A laundry treating apparatus capable of enhancing energy efficiency by recovering energy required for generating hot air and energy discharged to the outside may include, for example, a heat pump having, for example, two heat exchangers, a compressor and an expander, to recover energy from hot exhaust air and reuse it to heat air supplied to the drum to increase energy efficiency.

In detail, the heat pump may transmit thermal energy of high temperature and humidity air from the drum through the evaporator to a refrigerant, and may transmit thermal energy from the refrigerant to air flowing into the drum through the condenser, thereby generating hot air using discarded energy. The use of a heat pump may enhance energy efficiency in comparison to the case in which drying is performed using a heater.

In this manner, when the heat pump and the heater are both provided, hot air may be generated using only the heat pump or using both the heat pump and the heater. In particular, when both the heat pump and the heater, air may be quickly heated, in comparison to a case in which only the heat pump is actuated, shortening a drying time but increasing energy consumption but degrading energy efficiency. When the heater is operated during a drying process, a time for a refrigerant to reach evaporation pressure in an evaporator of the heat pump may be shortened, increasing pressure of a compressor driver of the heat pump.

The embodiment illustrated in FIGS. 1 through 4 is applied to a dryer, but embodiments are not limited only to a dryer, and may also be applicable to other laundry treating apparatus for drying laundry by supplying hot air into a drum, e.g., a washing machine also having a dry function, and the like.

The laundry treating apparatus shown in FIGS. 1 through 4 may include a body 100 forming the exterior and a drum 110 rotatably installed within the body 100. The drum may be rotatably supported by a supporter at, for example, front and rear end thereof.

The body 100 may include a door for opening and closing one end of the drum 110 to allow a drying target, or laundry items, to be put into the drum 110. Also, the body 100 may include a display displaying information such as a drying process mode, a drying progress degree, real-time energy efficiency, and the like, when a drying process is performed.

An intake duct 120 forming part of a flow path for transmitting air to the interior of the drum 110 may be installed below the drum 110. An end portion of the intake duct 120 may be connected to an end portion of a back duct 122 that extends in a vertical direction of the body 100 between the intake duct 120 and the drum 110 to supply air, which has passed through the intake duct 120, to the interior of the drum 110. Thus, a flow path transmitting air to the drum 110 may be formed by the intake duct 120 and the back duct 122.

Air supplied through the flow path may be introduced into the body 100 through an intake port formed in, for example, a rear surface or a lower surface of the body 100 from the outside and transferred to the intake duct 120. An intake fan 185 may be installed in an end portion of the intake duct 120 to induce air flow therein. Namely, in response to rotation of the intake fan 185, air within the body 100 may be introduced into the intake duct 120, and accordingly, pressure within the body 100 is lowered to allow ambient air to be introduced into the body 100 through the intake port.

In certain embodiments, it may not be necessary for air within the body 100 to be introduced, and for example air outside of the body 100 may also or instead be introduced.

A condenser 130 may be installed in front of the fan (i.e., up stream of the fan based on the air flow path). The condenser 130, together with an evaporator 135, a compressor 150, and an expander 160 as described hereinafter, may constitute a heat pump. the heat pump may include a heating medium circulating within the heat pump that is compressed by the compressor 150 and subsequently supplied to the condenser 130 through a first connection pipe 191 connecting the compressor 150 and the condenser 130. The heating medium may emit heat in the condenser 130 and be subsequently supplied to the expander 160 through a second connection pipe 192 connecting the condenser 130 and the expander 160. The heating medium expanded by the expander 160 may be supplied to an evaporator 135 through a third connection pipe 193 connecting the expander 160 and the evaporator 135. The heating medium may absorb heat in the evaporator 135 and be subsequently supplied to the compressor 150 through a fourth connection pipe 194 connecting the evaporator 135 and the compressor 150. In this manner, the heating medium circulates through the heat pump and acts as a refrigerant in the evaporator 135, so the heating medium will hereinafter be referred to as a refrigerant.

In the condenser 130, a single refrigerant pipe 134 may be disposed the air flow path, and a plurality of heat dissipation fins 132 may be installed perpendicular to the refrigerant pipe 134. Namely, the refrigerant pipe 134 may penetrate through the heat dissipation fins 132 disposed in layers at predetermined intervals therebetween. One end of the refrigerant pipe 134 may be connected to the first connection pipe 191 to receive a compressed refrigerant from the compressor 150, and the other end of the refrigerant pipe 134 may be connected to the second connection pipe 192 to supply a refrigerant to the expander 160. Since the intake fan 185 is positioned downstream of the condenser 130, air drawn in by the intake fan 185 may undergo heat-exchange with the refrigerant, while passing through the heat dissipation fins 132 of the condenser 130, and thus, air having an increased temperature may be introduced into the interior of the drum 110. In certain embodiments, a linear expansion valve whose opening degree is controlled by an electrical signal may be used as the expander 160.

The heater 170 may be installed within the back duct 122 to further heat air in a case in which air is not sufficiently or quickly enough heated by only the condenser 130. The heater 170 may also be installed in the intake duct 120. Air heated while passing through the condenser 130 and the heater 170 may be introduced as high temperature hot air into the interior of the drum 110 and subsequently dry a drying target accommodated within the drum 110.

Thereafter, the hot air is transmitted to an exhaust duct 140 by an exhaust fan 180, heat-exchanged with a low temperature refrigerant passing through the interior of the evaporator 135 disposed at an end portion of the exhaust duct 140, and subsequently discharged to the outside of the body 100. Through the heat-exchanging process, the air having a lower temperature and humidity may be discharged to the outside. At this time, a portion of thermal energy of the air discharged from the drum 110, passing through the evaporator 135, may be transmitted to the refrigerant, and the thermal energy may be used to heat air again in the condenser 130. Thus, since thermal energy, which would otherwise be discarded may instead be collected and recycled to generate hot air, energy consumption may be reduced. Also, in a case in which quick drying is required, the heater 170 may provide additional heat and drying may be performed flexibly.

When the heater 170 is operated together with the heat pump, energy efficiency may be degraded when compared to drying using only the heat pump. Also, when the heater 170 is continuously turned on during the drying operation, a time for the refrigerant to reach evaporation pressure in the evaporator 135 may be reduced, which may burden a driving device of the compressor 150. Thus, a sensing device for sensing a quantity or level of a state of a refrigerant circulating as a heating medium through the heat pump and a controller for controlling power of the heater 170 on the basis of the quantity or level of the state of the refrigerant may also be provided. The quantity or level of the state of the refrigerant may refer to qualities of a physical state such as a temperature or pressure of a refrigerant.

In certain embodiments, the sensing device may sense a temperature of a refrigerant, and may include a temperature sensor 137 that measures a temperature of the refrigerant discharged from the compressor 150. The temperature sensor 137 may be attached to the first connection pipe 191, such that it is adjacent to the compressor 150. A temperature of the refrigerant discharged from the compressor 150 may be inferred by measuring a temperature of a surface of the first connection pipe 191 adjacent to the compressor 150, so the temperature sensor 137 may simply be attached to the surface of the first connection pipe 191 to sense a temperature of the refrigerant.

The controller 200 may be electrically connected to the temperature sensor 137 and the heater 170, respectively, as described above, to control power of the heater 170 on the basis of the sensed temperature of the refrigerant. In detail, a method for controlling power of the heater 170 based on the temperature of the refrigerant will be described with reference to FIG. 4.

First, in a temperature sensing operation S110, a temperature of the refrigerant may be sensed by the temperature sensor 137. The sensed temperature of the refrigerant may be a temperature of the refrigerant when it is discharged from the compressor 150, and the sensing of the temperature of the refrigerant is starts to be measured when the compressor 150 is operated, and may subsequently be input as a TC0 to the controller 200. In a temperature comparison operation (S120), the controller 200 determines whether the temperature TC0 of the refrigerant discharged from the compressor is greater than or equal to a predetermined temperature value, e.g., 90 degrees. When the TC0 is lower than 90 degrees, the process may return to the temperature sensing operation (S110) and a temperature of the refrigerant discharged from the compressor sensed by the temperature sensor 137 may be continuously input as a TC0. When the temperature of the refrigerant discharged from the compressor is greater than or equal to 90 degrees, power to the heater 170 may be cut off by the controller 200 in a heater control operation (S130). A reference temperature value set as a comparison target in the temperature comparison operation (S120) may be changed according to a type of a refrigerant. Namely, a temperature TC0 at which power to the heater 170 is to be cut off may be changed according to a type of a refrigerant.

With the foregoing configuration, the temperature sensor 137 may be simply attached to the surface of the first connection pipe 191, simplifying assembly. Also, when the refrigerant is discharged from the compressor 150, it is in its highest energy state. Thus, power to the heater 170 may be cut off based on a temperature of the refrigerant when the energy thereof is at its highest level, whereby the heater 170 is effectively prevented from being actuated more than necessary, and thus overall energy efficiency may be enhanced.

In alternative embodiments, the temperature sensor 137 may be attached to a middle portion of the first connection pipe 191 or to a portion of the first connection pipe 191 adjacent to the condenser 130, as necessary, such as for conditions design, or the like. Also, a temperature value of the refrigerant as a reference for cutting off power to the heater 170 by the controller 200 may be changed according to a type of the refrigerant, a position at which the temperature sensor 137 is attached, a revolution per minute (RPM) of the compressor 150, and the like.

FIG. 5 is a flow chart of a process of controlling a heater according to temperature using the controller illustrated in FIG. 3 according to another embodiment as broadly described herein.

The controller 200 may be electrically connected to the temperature sensor 137 and the heater 170, respectively. and the controller 200 controls power to the heater 170 by calculating a difference between temperature variations or a pressure variations of the refrigerant sensed respectively by the temperature sensor 137 or a pressure sensor 139, for example, based on a difference between temperatures of the refrigerant or a difference between pressures of the refrigerant. One embodiment for this method using temperature differences will be described in detail with reference to FIG. 5. However, it is pointed out that instead of temperature differences, also pressure differences can be used in this embodiment.

First, in a temperature sensing operation (S210 to S240), a temperature of the refrigerant is sensed by the temperature sensor 137, e.g. as illustrated in FIG. 2. Here, the temperature sensor 137 senses temperatures of the refrigerant discharged from the compressor 150 several times, at predetermined intervals. Of course, also other positions of the temperature sensor 137 are possible, e.g. as shown in FIGS. 6 and 7 (described below).

In detail, in the first sensing operation (S210), a temperature of the refrigerant at a first point in time is sensed by the temperature sensor 137. The first point in time may refer to a time when t1 seconds, e.g., 30 seconds, has elapsed since operation of the compressor 150 was initiated.

In the second sensing operation (S220), a temperature of the refrigerant at a second point in time is sensed by the temperature sensor 137. The second point in time refers to a time when t2 seconds (e.g., 130 seconds) has lapsed since operation of the compressor 150 was initiated. Alternatively, the second point in time may be a point in time when a predetermined time (Δt) has lapsed after the first point. Specifically, t2 seconds may be defined as the sum of t1 seconds and the predetermined time (Δt).

In the third sensing operation (S230), a temperature of the refrigerant at a third point in time is sensed by the temperature sensor 137. The third point in time may be a point in time when t3 seconds has lapsed after operation of the compressor 150 was initiated.

In the fourth sensing operation (S240), a temperature of the refrigerant at a fourth point in time may be sensed. The fourth point in time may be defined as a point in time when t4 seconds has lapsed after operation of the compressor 150 was initiated. Alternatively, the fourth point in time may be defined as any point in time after t2, and the third point in time may be defined to be a point in time by the predetermined time (Δt) ahead of the fourth point in time. Thus, when t1 seconds is e.g. 30 seconds and Δt is e.g. 100 seconds, t2 seconds is 130 seconds. And t3 seconds may be any point in time after 130 seconds, and t4 seconds is Δt after t3 seconds, e.g. by 100 seconds later than t3.

The controller 200 may input the temperature of the refrigerant when t1 seconds has lapsed after operation of the compressor 150 was started, as TC1, and may input the temperature of the refrigerant when t2 seconds has lapsed after the compressor 150 was stored, as TC2. The controller 200 may also input the temperature of the refrigerant when t3 seconds has lapsed after the compressor 150 was started, as TC3, and may input the temperature of the refrigerant when t4 seconds has lapsed after the compressor 150 was started, as TC4.

In certain embodiments, in the sensing operation (S210 to S240), the temperature sensor 137 may also continuously sense the temperature of the refrigerant discharged from the compressor 150, starting from when operation of the compressor 150 is initiated, and the controller 200 may input the temperatures of the refrigerant corresponding to a first to nth points in time, as TC1 to TCn (n being an integer>=4).

In the comparison operation (S250), the controller 200 may calculate a temperature variation during the predetermined time Δt on the basis of the previously input TC1 to TC4 as expressed by Equation 1 below, and compare the same with a predetermined value. After receiving TC1 and TC2, the controller 200 may determine an initial temperature variation, i.e. by calculating the slope (TC2-TC1)/(t2-t1). The value of the initial temperature variation may be stored in order to be used for comparison with a current temperature variation. For example, the controller 200 may calculate the initial temperature variation for Δt (100 seconds) from the first point in time to the second point in time and an average temperature variation for Δt (100 seconds) from the third point in time to the fourth point in time. Thereafter, a difference value between the temperature variation from the first point in time to the second point in time and the temperature variation from the third point in time to the fourth point in time may be determined. Thereafter, the controller 200 may determine whether the difference value between the temperature variations is greater than or equal to a predetermined value, e.g. 0.05 degrees/sec.

$\begin{matrix} {\frac{\left( {{{TC}\; 2} - {{TC}\; 1}} \right)}{100\mspace{14mu} {\sec.}} - \frac{\left( {{{TC}\; 4} - {{TC}\; 3}} \right)}{100\mspace{14mu} {\sec.}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack \end{matrix}$

In step S250, the value calculated by Equation 1 is compared with a predetermined value. When the value calculated by Equation 1 is less than the predetermined value, e.g. is less than 0.05 degrees/sec, the controller 200 returns to the third sensing operation (S230). Here, the controller 200 inputs a refrigerant temperature at a point in time 100 seconds (Δt) earlier from a current point in time, as TC3. In the fourth sensing operation (S240), the temperature sensor 137 senses a temperature of the refrigerant discharged from the compressor at the current point in time, and the controller 200 inputs the temperature of the refrigerant at the current point in time, as TC4, and repeatedly performs the comparison operation (S250) based on the initial temperature variation stored in the memory. In the comparison operation (S250), when the value calculated by Equation 1 is greater than or equal to e.g. 0.05 degrees/sec, power of the heater 170 is cut off in the heater control operation (S260). Instead of the initial temperature variation, a value of the previous temperature variation that was measured prior to the current temperature variation may be used in the comparison operation (S250). In this case, also Equation 1 may be used, with TC2-TC1 referring to the previous temperature variation measured prior to the current temperature variation. If the comparison result of Equation 1 is less than a predetermined value, the heater is controlled to be switched off in the heater control operation (S260).

The predetermined value used as a reference for determining whether to cut off power to the heater 170 by the controller 200 may be changed according to a type of a refrigerant, and other factors and characteristics as appropriate .

According to the foregoing configuration, based on the temperature variation of the refrigerant for the predetermined time (Δt), when a current temperature variation (i.e., the temperature variation from the third point of time to the fourth point in time) is significantly reduced in comparison to the previous temperature variation (i.e., the temperature variation from the first point in time to the second point in time), it may indicate that a rate at which a temperature of air heated by the heater 170 is increased is less than that of the previous time, and, power to the heater 170 is cut off, enhancing energy efficiency. Also, although a temperature or a pressure of the refrigerant may be changed according to the RPM of the compressor 150, a temperature variation or a pressure variation of the refrigerant is not affected by the RPM of the compressor 150. Thus, a point in time at which power to the heater 170 is to be cut off may be more accurately determined.

FIG. 6 is a schematic view of a heat pump and a sensing device according to another embodiment, FIG. 7 illustrates temperature sensing device installed in a condenser illustrated in FIG. 6, and FIG. 8 is a flow chart of a process of controlling the heating device according to a temperature by a controller illustrated in FIG. 6.

The clothes treating apparatus having a heat pump according to another embodiment as broadly described herein may include a heat pump and a heater, and configurations of the heat pump and the heater may be substantially the same as those described above, so a detailed description thereof will be omitted.

The sensing device for sensing a temperature of a refrigerant may include the temperature sensor 137 to measure a temperature of a refrigerant flowing in the refrigerant pipe 134 of the condenser 130. As illustrated in FIGS. 6 and 7, the temperature sensor 137 may be attached to a U-shaped bent portion at the halfway point of the refrigerant pipe 134. Here, FIG. 6 is a plan view of the heat pump viewed downwardly, and FIG. 7 is a side view of an arrangement of the refrigerant pipes 134 when the condenser 130 illustrated in FIG. 6 is viewed from the side. A temperature of a refrigerant may be inferred by measuring a surface temperature of the refrigerant pipe 134, so a temperature of a refrigerant may be sensed by simply attaching the temperature sensor 137 to the surface of the refrigerant pipe 134.

According to the foregoing configuration, since the temperature sensor 137 is attached to a portion positioned outside of stacked heat dissipation pins 132, rather than to a portion positioned between the heat dissipation pins 132 of the refrigerant pipe 134, the temperature sensor 137 may accurately sense a temperature of the refrigerant without being affected by air flowing between the heat dissipation fins 132.

As illustrated in FIG. 3, the controller 200 is electrically connected to the temperature sensor 137 and the heater 170, respectively, to control power of the heater 170 based on a temperature of the refrigerant sensed by the temperature sensor 137. In detail, a method for controlling power to the heater 170 based on a temperature of a refrigerant by the controller 200 will be described with reference to FIG. 8.

First, in a temperature sensing operation (S310), the temperature sensor 137 senses a temperature of a refrigerant in the condenser 130 when the compressor 150 is actuated. The sensed temperature TCC of the refrigerant is a temperature of the refrigerant flowing in the refrigerant pipe 134 of the condenser 130, and in this case, since the temperature sensor 137 is attached to a middle portion of the refrigerant pipe 134, a temperature of the refrigerant heat-exchanged with air drawn into the drum to a degree is sensed. The sensed temperature of the refrigerant in the condenser 130 is input as TCC to the controller 200.

In a temperature comparison operation (S320), the controller 200 determines whether the temperature (TCC) of the refrigerant of the condenser 130 is greater than or equal to a predetermined temperature value, e.g., 80 degrees. When the temperature TCC is lower than 80 degrees, the process may return to the temperature sensing operation (S310) and a temperature of the refrigerant may be continuously sensed by the temperature sensor 137. The sensed temperature of the refrigerant is input as TCC to the controller 200. When the temperature TCC of the refrigerant is greater than or equal to 80 degrees, power to the heater 170 may be cut off by the controller 200 in a heater control operation (S330). However, the reference temperature of the refrigerant for determining whether to cut off power to the heater 170 may be changed according to a type of the refrigerant.

According to the foregoing configuration, since the temperature sensor 137 is simply attached to the surface of a portion of the refrigerant pipe 134 protruded in a U-like shape in the condenser 130, the assembly process may be simplified. Also, according to the foregoing configuration, since the temperature sensor 137 is attached to a middle portion of the refrigerant pipe 134, a temperature of the refrigerant appropriately heat-exchanged in the condenser 130 may be sensed, and when the temperature TCC of the refrigerant is greater than or equal to a predetermined temperature, there is no need to re-heat air using the heater 170, and the power to the heater 170 may be cut off to prevent the heater 170 from being unnecessarily actuated, enhancing energy efficiency.

An attachment position of the temperature sensor 137 to the refrigerant pipe 134 may be changed as necessary, for example, for design reasons and the like. Also, the temperature value used as a reference for determining whether to cut off power to the heater 170 by the controller 200 may be changed according to a type of the refrigerant, the attachment position of the temperature sensor 137, and the like.

FIGS. 9 to 11 illustrate heat pumps and sensing devices according to other embodiments, FIG. 12 is a block diagram of a system for controlling a heating device of the embodiments illustrated in FIGS. 9 to 11, and FIG. 13 is a flow chart of a process for controlling a heating device according to pressure by a controller as shown in FIG. 12.

The sensing device sensing pressure of a refrigerant may include a pressure sensor 139 that measures pressure of a refrigerant in a high pressure state. For example, as illustrated in FIG. 9, the pressure sensor 139 may be installed in the first connection pipe 191 supplying a refrigerant discharged from the compressor 150 to the condenser 130. In this case, the pressure sensor 139 may be installed on the first connection pipe 191 such that it is adjacent to the compressor 150 to measure pressure of the refrigerant discharged from the compressor 150. Alternatively or additionally, as illustrated in FIG. 10, the pressure sensor 139 may be installed in the refrigerant pipe 134 provided in the condenser 130 to measure pressure of the refrigerant in the condenser 130. Alternatively or additionally, as illustrated in FIG. 11, the pressure sensor 139 may be installed in the second connection pipe 192 supplying the refrigerant discharged from the condenser 130 to the expander 160 to measure pressure of the refrigerant before being introduced into the expander 160.

As illustrated in FIG. 12, a controller 200′ may be electrically connected to the pressure sensor 139 and the heater 170 to control power to the heater 170 based on the pressure of the refrigerant sensed by the pressure sensor 139. A method for controlling power to the heater 170 based on refrigerant pressure will be described with reference to FIG. 12.

First, in a pressure sensing operation (S410), the pressure sensor 139 senses pressure of a refrigerant. The sensed pressure of the refrigerant may be a pressure measured when the refrigerant is in a high pressure state in the heat pump, and may be pressure sensed from one of the first connection pipe 191, the refrigerant pipe 134, or the second connection pipe 192. Pressure of the refrigerant is measured when the compressor 150 operates, and subsequently input as Pd to the controller 200′. A unit of pressure is bar.

In a pressure comparison operation (S420), the controller 200′ determines whether the pressure Pd of the refrigerant is greater than or equal to a predetermined pressure, e.g., 28 bar. When the pressure Pd of the refrigerant is lower than 28 bar, the process may return to the pressure sensing operation (S410) and pressure of the refrigerant sensed by the pressure sensor 139 is input as Pd. Meanwhile, when the pressure Pd of the refrigerant is greater than or equal to 28 bar, power to the heater 170 is cut off by the controller 200′ in a heater control operation (S430). The reference predetermined pressure for determining whether to cut off power of the heater 170 may be changed according to a type of a refrigerant, location of the pressure sensor 139, and other such factors.

According to the foregoing configuration, since pressure of the refrigerant is directly measured, power of the heater 170 may be cut off before the pressure reaches to a level at which the driving device of the compressor 150, and the like, is overtasked, and thus, durability of the compressor 150 may be enhanced and energy efficiency may be increased.

FIG. 14 is a flow chart of a method for controlling a laundry treating apparatus having a heat pump, according to an embodiment as broadly described herein. As previously described, the laundry treating apparatus having a heat pump may perform a general drying process by actuating only a heat pump, or may perform a speed drying process by actuating both the heat pump and the heater 170. FIG. 14 is a flow chart of a method for controlling the heater 170 during a speed drying process.

First, when the speed drying process is selected, power is applied to the heat pump in a power applying operation (S10) and power is applied to the heater 170. Next, in a temperature sensing operation (S21), a temperature of a refrigerant is sensed by the temperature sensor 137. Thereafter, in a heater control operation (S31), power to the heater 170 is cut off by the controller 200 according to the temperature of the refrigerant. A detailed control method has been described above with reference to FIGS. 4 and 5.

FIG. 15 is a flow chart of a method for controlling a laundry treating apparatus having a heat pump, according to another embodiment as broadly described herein. First, like the embodiment as described above, when the speed drying process is selected, power is applied to the heat pump and power is applied to the heater 170 in the power applying operation (S10). Next, in a pressure sensing operation (S22), pressure of the refrigerant is sensed by the pressure sensor 139 as described above with reference to FIGS. 9 through 13. Thereafter, in a heater control operation (S32), power to the heater 170 is cut off by the controller 200′ based on the basis of pressure of the refrigerant as described above. A detailed control method has been described above with reference to FIG. 13. Another control method has been described above with reference to FIG. 5 using temperature as characteristic of the heating medium. However, as also mentioned above, the method of FIG. 5 may also be applied using pressure as characteristic of the heating medium.

According to the control method according to the foregoing embodiments, the heat pump and the heater 170 may be simultaneously actuated at an early stage to perform speed drying, and since power to the heater 170 may be cut off by determining a point in time at which the speed drying effect by the heater 170 is slowed based on a quantity or level of a state of the refrigerant, such as a refrigerant temperature (variation) or a refrigerant pressure (variation), energy efficiency in the remaining drying process may be increased and durability of the heat pump may be enhanced.

A laundry treating apparatus is provided that is capable of increasing energy efficiency when a heat pump and a heating unit are operated together during a drying process, and that is capable of controlling power of the heating unit on the basis of a physical parameter value of a heating medium circulating in the heat pump in order to prevent damage to the heat pump.

A method for controlling a laundry treating apparatus is provided that is capable of increasing energy efficiency when a heat pump and a heating unit are operated together during a drying process, and that is capable of controlling power of the heating unit on the basis of a physical parameter value of a heating medium circulating in the heat pump in order to prevent damage to the heat pump.

A laundry treating apparatus having a heat pump, as embodied and broadly described herein, may include a drum for accommodating a dry target; a heat pump configured to cool air transmitted from the drum and subsequently heat the same; a heating unit configured to heat air transmitted from the heat pump to the drum; a sensing unit configured to sense a physical parameter value of a heating medium; and a control unit configured to control the heating unit on the basis of the physical parameter value of the heating medium.

The heat pump may include a heating medium that circulates; a compressor configured to compressor the heating medium; a condenser configured to heat air transmitted to the drum; an expander configured to expand the heating medium; and an evaporator configured to cool air transmitted from the drum.

The control of power of the heating unit may include switching off the heating unit, so that only the heat pump is operated. Preferably, the heating unit is switched off under a condition of the heating medium indicating that a stable state of heating has been reached. Thus, the object of fast heating has been achieved and a heating using only the heat pump may be sufficient. By switching now off the heating unit, energy consumption can be decreased.

Preferably, when a variation in the physical parameter value (e.g. temperature, pressure) is reduced compared with an initial variation in the physical parameter value of the heating medium by more than a predetermined numerical value, the control unit is configured to cut off power of the heating unit. That is, if (initial variation)−(current variation)>a, the heater is switched off. Similarly, when a difference between a currently sensed physical parameter value (variation) and a previously sensed physical parameter value (variation) of the heating medium is less than a predetermined numerical value a, the control unit may be configured to cut off power of the heating unit. That is, if (current value)−(previous value) <b, and/or (previous variation)−(current variation)<c, the heater is switched off.

The control unit may be configured to operate the heating unit and the heat pump simultaneously or only one thereof. During hot air supply to the drum, the heating unit is preferably switched off, if a desired drum temperature is reached. Thus, the control unit may be configured to power off the heating unit, if the drum temperature is equal to or higher than a predetermined value.

The sensing unit may include at least one temperature sensing unit and/or at least one pressure sensing unit for sensing the temperature and/or pressure of the heating medium in the heat pump. The control unit may control the heating unit based on a temperature of the heating medium and/or based on a pressure of the heating medium.

The temperature sensing unit may be installed in a first connection pipe in which the heating medium flows from the compressor to the condenser. Here, the temperature sensing unit may be installed to be adjacent to the compressor to sense a temperature of the heating medium discharged from the compressor.

The condenser may include a condenser heating medium pipe in which the heating medium flows, wherein the temperature sensing unit may be installed in the condenser heating medium pipe. Preferably, the temperature sensing unit may also be installed in the halfway point of the condenser heating medium pipe. Therefore a temperature of the heating medium appropriately heat-exchanged in the condenser 130 may be sensed.

Also, when a temperature of the heating medium is equal to or higher than a predetermined numerical value, the control unit may cut off power of the heating unit.

Also, the temperature of the heating medium may be used as a measure for the drum temperature. Thus, when a current temperature of the heating medium is equal to or higher than a predetermined numerical value, the control unit may cut off power of the heating unit. Alternatively or additionally, when a temperature variation or increase of the heating medium for a predetermined period of time is reduced from an initial temperature variation or increase of the heating medium by more than a predetermined numerical value, the control unit may cut off power of the heating unit.

Generally, the term temperature variation may refer to a temperature average between two points in time, i.e. the difference of the temperatures sensed at these two time points divided by the time interval there between, or a gradient, i.e. slope, of the temperature curve (temperature vs. time). Likewise, if the slope of the temperature curve (temperature vs. time) at a certain time point flattens below a predetermined value or if a difference between the current slope (variation) and the previous slope (variation) is less than a predetermined value, the heating unit may be switched off. In this situation, the heating operation has reached a stable state, in which the temperature of the heating medium remains nearly constant. Therefore, the additional heating by the heating unit used for increased heating rate is not necessary any longer. By these means, the heat efficiency of the laundry treatment apparatus can be optimized.

The pressure sensing unit may be installed in at least one of a first connection pipe in which the heating medium flows from the compressor to the condenser, a condenser heating medium pipe in which the heating medium flows in the condenser, and a second connection pipe in which the heating medium flows from the condenser to the expander.

When pressure of the heating medium is equal to or greater than a predetermined numeral value, the control unit may cut off power of the heating unit.

Also, the pressure of the heating medium may be used as a measure for the drum temperature. Thus, when a current pressure of the heating medium is equal to or higher than a predetermined numerical value, the control unit may cut off power of the heating unit. Alternatively or additionally, when a pressure variation or increase of the heating medium for a predetermined period of time is reduced from an initial pressure variation or increase of the heating medium by more than a predetermined numerical value, the control unit may cut off power of the heating unit. Likewise, if the slope of the temperature curve (temperature vs. time) flattens below a predetermined value or if a difference between the current slope and a previous slope is less than a predetermined value, the heating unit may be switched off. In this situation, the heating operation has reached a stable state, in which the pressure of the heating medium remains nearly constant. Therefore, the additional heating by the heating unit used for increased heating rate is not necessary any longer. By these means, the heat efficiency of the laundry treatment apparatus can be optimized.

The initial temperature variation and/or previous pressure variation may refer to a respective initial variation measured after powering up the heat pump, e.g. after a predetermined time t1. This value may be stored in a memory. Alternatively or additionally, the previous temperature variation and/or previous pressure variation may refer to the respective value measured before a current temperature variation and/or current pressure variation. Thus, the temperature variation and/or pressure variation may be determined repeatedly, and a difference between two subsequent temperature variations and/or pressure variations may be used for comparison with a predetermined value. If this difference is lower than the predetermined value, the heating unit may be switched off.

A method for controlling a laundry treating apparatus having a heat pump and a heating unit, as embodied and broadly described herein may include a hot air supplying operation of supplying hot air to a drum by applying power to the heat pump and the heating unit; a sensing operation of sensing at least one physical parameter value of a heating medium that circulates in the heat pump; and a heating unit control operation of controlling power of the heating unit on the basis of the physical parameter value of the heating medium. The method may be used by a control unit in a clothes treating apparatus according to any one of the above described embodiments. Preferably, during at least a part of the hot air supplying operation, the heat pump and the heating unit are operated simultaneously.

The physical parameter value of a heating medium may comprise a temperature and/or a pressure of the heating medium.

In heater control operation, as embodied and broadly described herein when a temperature and/or pressure of the heating medium is greater than or equal to a respective predetermined numerical value, power of the heater may be cut off. Alternatively or additionally, when a temperature variation and/or a pressure variation of the heating medium is reduced from a previous temperature variation and/or pressure variation of the heating medium by more than a predetermined numerical value, power to the heater may be cut off.

A temperature of the heating medium may include at least one of a temperature of the heating medium discharged from a compressor of the heat pump or a temperature of the heating medium that flows within a condenser of the heat pump.

Pressure of the heating medium may include at least one of pressure of the heating medium that flows from the compressor of the heat pump to the condenser of the heat pump, pressure of the heating medium that flows within the condenser, or pressure of the heating medium that flows from the condenser of the heat pump to an expander of the heat pump

According to embodiments as broadly described herein, laundry may be quickly dried by actuating both the heat pump and the heating unit simultaneously and/or alternately, and since the heater is controlled based on a change in material properties of a heating medium, energy efficiency may be enhanced.

Also, according to embodiments as broadly described herein, since the heating medium is prevented from being heated by controlling the heater according to a change in the physical properties of the heating medium, durability of the heat pump may be enhanced.

In addition, according to embodiments as broadly described herein, since a point in time at which power of the heater is to be controlled is determined based on pressure and/or temperature of the heating medium, an ON/OFF operation of the heater may be precisely controlled.

Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art. 

What is claimed is:
 1. A laundry treating apparatus, comprising: a drum; a heat pump circulating a heating medium, the heat pump including a compressor configured to compress the heating medium, a condenser configured to heat air to be supplied to the drum, an expander configured to expand the heating medium, and an evaporator configured to cool air received from the drum; a heater configured to heat air transmitted from the heat pump to the drum; a sensing device configured to sense at least one characteristic of the heating medium; and a controller configured to control the heater based on the sensed characteristic of the heating medium.
 2. The apparatus of claim 1, wherein the characteristic of the heating medium includes at least one of a temperature and a pressure of the heating medium.
 3. The apparatus of claim 2, wherein the controller is configured to discontinue a supply of power to the heater when a temperature and/or a pressure of the heating medium is greater than or equal to a predetermined numerical value.
 4. The clothes treating apparatus of claim 2, wherein the controller is configured to discontinue a supply of power to the heater when a current temperature variation of the heating medium corresponding to a current period of time is less than an initial temperature variation of the heating medium corresponding to an initial period of time by more than a predetermined numerical value, and/or wherein the controller is configured to discontinue a supply of power to the heater when a current pressure variation of the heating medium corresponding to a current period of time is less than an initial pressure variation of the heating medium corresponding to an initial period of time by more than a predetermined numerical value.
 5. The clothes treating apparatus of claim 2, wherein the controller is configured to discontinue a supply of power to the heater when a temperature difference between a currently sensed temperature and a previously sensed temperature of the heating medium is less than a predetermined numerical value, and/or wherein the controller is configured to discontinue a supply of power to the heater when a pressure difference between a currently sensed pressure and a previously sensed pressure of the heating medium is less than a predetermined numerical value.
 6. The apparatus of claim 2, wherein the controller is configured to discontinue a supply of power to the heater when a current temperature variation of the heating medium corresponding to a current period of time is less than a previous temperature variation of the heating medium corresponding to a previous period of time by more than a predetermined numerical value, and/or wherein the controller is configured to discontinue a supply of power to the heater when a current pressure variation of the heating medium corresponding to a current period is less than a previous pressure variation of the heating medium corresponding to a previous period of time by more than a predetermined numerical value.
 7. The apparatus of claim 2, wherein the sensing device comprises at least one of a temperature sensor configured to sense a temperature of the heating medium, and a pressure sensor configured to sense a pressure of the heating medium.
 8. The apparatus of claim 7, wherein the temperature sensor is installed in a flow path of the heating medium between the compressor and the condenser.
 9. The apparatus of claim 8, wherein the temperature sensor is installed adjacent to the compressor.
 10. The apparatus of claim 7, wherein the temperature sensor is installed in a flow path of the heating medium within the condenser.
 11. The apparatus of claim 10, wherein the temperature sensor is installed at an intermediate portion of the flow path of the heating medium within the condenser.
 12. The apparatus of claim 7, wherein the pressure sensor is installed in at least one of a flow path of the heating medium between the compressor and the condenser, a flow path of the heating medium within the condenser, and a flow path of the heating medium between the condenser and an expander.
 13. A method for controlling a laundry treating apparatus having a heat pump and a heater, the method comprising: applying power to the heat pump and the heater to heat air, and supplying the heated air to a drum; sensing at least one predetermined characteristic of a heating medium circulating in the heat pump; and controlling power to the heater based on the sensed predetermined characteristic of the heating medium.
 14. The method of claim 13, wherein the predetermined characteristic of the heating medium includes at least one of a temperature and a pressure of the heating medium.
 15. The method of claim 14, wherein controlling power to the heater based on the sensed predetermined characteristic of the heating medium comprises discontinuing a supply of power to the heater when a sensed temperature and/or a sensed pressure of the heating medium is greater than or equal to a predetermined numerical value.
 16. The method of claim 14, wherein controlling power to the heater based on the sensed predetermined characteristic of the heating medium comprises discontinuing a supply of power to the heater when a current temperature variation corresponding to a current period of time is less than a previous temperature variation corresponding to a previous period of time by more than a predetermined numerical value.
 17. The method of claim 14, wherein a temperature of the heating medium comprises at least one of a temperature of the heating medium as it is discharged from a compressor of the heat pump or a temperature of the heating medium as it flows within a condenser of the heat pump.
 18. The method of claim 14, wherein a pressure of the heating medium comprises at least one of pressure of the heating medium as it flows from the compressor of the heat pump to the condenser of the heat pump, pressure of the heating medium as it flows within the condenser, or pressure of the heating medium as it flows from the condenser to an expander of the heat pump. 